The present invention is directed to an optoelectronic device for coupling different dimensioned waveguides, which device comprises means for a narrow wave guidance in the lateral direction and means for a broad wave guidance in the lateral direction, said two means being arranged to extend parallel to one another with one of the means being continually reduced in a transversal direction in a section so that both a narrow and a broad wave are guided in a region adjacent this section and only one of the waves is guided in the region on the other side of this section.
A critical condition for optoelectronic transmission technology is the effective, stable and simple adjustable optical coupling between an optical fiber as a transmission medium and an optoelectronic device as either a transmission element or as a reception element. To this end, the electromagnetic (EM) field distribution crosswise (either transversely or laterally) vis-a-vis the propagation direction of the light in the optical fiber must be matched to the field distribution in the optoelectronic device. The wave guidance in the optoelectronic device (OED) generally occurs with waveguides wherein the electromagnetic field distribution crosswise vis-a-vis the propagation direction of the light differs greatly from that which is in an optical fiber. A matching of the wave guidance between the optoelectronic device and the optical fiber is achieved with the assistance of an adiabatic taper. Such an adiabatic taper is composed of a waveguide whose lateral and transversal wave guidance changes along the propagation direction of the light so that no optical losses due to conversion of modes will occur. To this end, the geometric shape of the waveguide in the optoelectronic device is hitherto varied along the propagation of the light, both in a lateral, as well as a transverse, direction. For example, see an article by A. Shahar et al entitled "Dynamic etch mask technique for fabricating tapered semiconductor optical waveguides and other structures", Appl. Phys. Lett., Vol. 56, No. 12, Mar. 19, 1990, pp 1098-1100. Technological measures for varying the geometric dimensions in both direction perpendicular to the light propagation are required for this purpose.